COGENT Tutorial Description

COGENT Tutorial Description

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An Introduction to the COGENT Cognitive Modelling Environment Richard P. Cooper (R.Cooper@bbk.ac.uk) School of Psychology, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK The COGENT Environment COGENT (Cooper & Fox, 1998; Cooper 2002) is a graphical environment that is designed to simplify the process of developing and evaluating computational models of high-level cognitive processes. COGENT does not embody any particular theory of the cognitive architecture, nor is it a general purpose programming language. Rather it provides a set of primitives that may be assembled and configured to yield a variety of models in many different domains. COGENT has been used extensively for teaching cognitive modelling at numerous institutions in Europe and the US. It also has applications in modelling research. The basic system provides the modeller with a sketch pad on which a model may be drawn as a box and arrow diagram (see Figure 1). This level of description provides the psychologist with a familiar notation, thus simplifying the modelling processes, but is inadequate for a Figure 1: A COGENT box and arrow diagram of computationally complete specification. In order to fully Atkinson & Shiffrin’s Modal Model of memory specify a COGENT model the boxes in each diagram must be fleshed out, either by specifying computational properties environment within the one system, and participants will be (such as capacity limitations or decay ...

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An Introduction to the COGENT Cognitive Modelling Environment
Richard P. Cooper (R.Cooper@bbk.ac.uk)
School of Psychology, Birkbeck, University of London,
Malet Street, London, WC1E 7HX, UK
The COGENT Environment
COGENT (Cooper & Fox, 1998; Cooper 2002) is a
graphical environment that is designed to simplify the
process of developing and evaluating computational models
of high-level cognitive processes. COGENT does not
embody any particular theory of the cognitive architecture,
nor is it a general purpose programming language. Rather it
provides a set of primitives that may be assembled and
configured to yield a variety of models in many different
domains. COGENT has been used extensively for teaching
cognitive modelling at numerous institutions in Europe and
the US. It also has applications in modelling research.
The basic system provides the modeller with a sketch pad
on which a model may be drawn as a box and arrow
diagram (see Figure 1). This level of description provides
the psychologist with a familiar notation, thus simplifying
the
modelling
processes,
but
is
inadequate
for
a
computationally complete specification. In order to fully
specify a COGENT model the boxes in each diagram must
be fleshed out, either by specifying computational properties
(such as capacity limitations or decay rates of buffers) or by
adding production-like rules. Structured editors are provided
to simplify the process of writing rules, and to ensure that
the resultant rules are syntactically well-formed.
COGENT also includes tools for model evaluation. Its
model execution environment embodies the notion of a
subject or “virtual participant”, as well as notions from
standard experimental psychology of trial and block. These
provide hooks that help bridge the gap between empirical
psychology and cognitive modelling. Thus, it is possible to
define virtual subjects with different memory spans and
compare their performance over several trials of a task (for
example). Integrated tools allow behavioural measures to be
graphed or tabulated, simplifying the interpretation of model
output.
For further details of COGENT, including versions of the
software for a variety of platforms and detailed tutorial
notes, see http://cogent.psyc.bbk.ac.uk/
Tutorial Description
The tutorial will begin with a brief tour of the COGENT
system aimed at demonstrating some of the environment’s
capabilities and giving attendees a clear understanding of its
intended purpose. This will be followed by a hands-on
session in which participants will work through the
implementation of a well-known cognitive theory: the
Modal Model of memory (Atkinson & Shiffrin, 1968).
COGENT allows users to specify both a model and a task
environment within the one system, and participants will be
provided with a sophisticated task environment within
which their implementation of the Modal Model will be
developed. This will allow participants to test their models
on the standard free recall memory task.
Figure 1: A COGENT box and arrow diagram of
Atkinson & Shiffrin’s Modal Model of memory
The second half of the tutorial will focus on the role of
parameters within COGENT models and participants will
examine the effects of parameter variation on their model’s
behaviour. Thus, we will consider how capacity limitations
and decay in the buffers that make up the Modal Model
affect behaviour on the standard free recall task. The goal
will be to reproduce the U-shaped free-recall curves that
originally motivated the development of the Modal Model.
The tutorial will conclude with a review of recent extensions
to the COGENT environment.
References
Atkinson, R. C. & Shiffrin, R. M. (1968): Human memory:
A proposed system and its control processes. In K. W.
Spence
(ed.),
The
Psychology
of
Learning
and
Motivation: Advances in research and theory, Volume 2
.
pp. 89–195. New York: Academic Press.
Cooper, R. P. (2002):
Modelling High-Level Cognitive
Processes.
Lawrence Erlbaum Associates. (Includes
contributions from P. Yule, J. Fox and D. W. Glasspool.)
Cooper, R. P. & Fox, J. (1998): COGENT: A visual design
environment for cognitive modelling.
Behavior Research
Methods, Instruments & Computers. 30
, 553–564.
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